Rest every 3 weeks?

I just started doing the Westside for Skinny Bastards program a few weeks ago. It's the first I've done any serious weight training, and all the reading I've been doing on the subject is pretty damn confusing considering everyone says something slightly different. I've read about taking a 'rest' week every three weeks or so, and this week I happen to be doing this although it's due to a shoulder/upper back strain from BJJ and not a planned part of my program.
My first question: Will it benefit me in building strength to not do WS4SB for a week every 3 weeks? My goal with lifting is to increase overall strength for MMA purposes, and I'd actually like to avoid increasing size, or at least weight if possible.
Second question: Assuming there is some benefit, should I just do cardio (I swim for my cardio work) those days, nothing at all, or can I do something simple like pushups and crunches to stay warm?

One thing I've noticed after this week is that after 4-5 days of not doing anything I start to get ancy and find it hard to sleep. Since I work nights, sleeping is already hard enough so if the rest week is useful I'd like to find something to replace the lifting to get my body tired.

You don't need to actually stop lifting, but switch to a new max effort movement every 2-3 weeks. So, if you've been benching for 2-3 weeks, switch to a different movement (like weighted dips, rack lockouts, military presses, etc).

Yeah, 1-3 weeks works as a general guideline. If you have specific lifting goals (like, increase bench by 5lbs in 4 weeks), you would switch your ME lift around that goal (so, say that you get stuck 6 inches from your chest on bench. You would pick rack lockouts from the 6 inch mark as your new ME lift and nail that for a few weeks before switching back to bench or picking a new ME lift). If you're just trying to get some strength though, a variety of lifts is fine.

The street argument is retarded. BJJ is so much overkill for the street that its ridiculous. Unless you're the idiot that picks a fight with the high school wrestling team, barring knife or gun play, the opponent shouldn't make it past double leg + ground and pound - Osiris